Combination high fidelity system



y 1961 A. K. TATEISHI ETAL 2,983,795

COMBINATION HIGH FIDELITY SYSTEM 2 Sheets-Sheet 2 Filed Nov. 18, 1957 FMon #28 aux o 955 D 9 F200 58 mg mzo: Jo 222 k Avk hm mm on INVENTORSARTHUR KTATEISHI JOHN STAFFORD United States Patent:

COMBINATION men FIDELITY SYSTEM Arthur K. Tateishi and John E. Stafford,Toronto, On-

tario, Canada, assignors to Seabreeze Manufacturing Limited I Filed Nov.18, 1957, Ser. No. 697,274

17 Claims. (Cl. 179-10011) This invention relates to improvements insound reproduction and recording systems, and more particularly to highfidelity or hi-fi systems.

In an effort to meet the demand for increased functions and versatilityof high fidelity systems, such systems have become extremely complex andexpensive, putting them beyond the reach of all but a few, Moreover, asfunctions have been added to the systems they have not only grownelectrically complex, but very bulky, requiring either custominstallation or at best forming a bulky piece of furniture which isawkward to arrange. Even in their most elaborate forms, such presenthi-fi systems do not afford the listener all of the versatility offunctioning which 'may be desired.

It is the object of this invention to provide a complete high fidelitysystem, includingin' particular a stereophonic sound system, which willbe extremely simple to operate and which will be more versatile andflexible than even the present most elaborate custom built system, yetwhich can be economically produced, and sold at a price within the meansof purchasers of the ordinary better quality .radio phonograph sets. V r

In this connection, it is an important object to provide --a system asaforesaid which can be broken down into :component units that'can simplybe plugged together in a simple manner in assembling the system, wherebythe system may be purchased unit by unit'and built up into its ultimateversatility and flexibility over a period of time according to the meansof the purchaser.

-Still another important object is to provide a system as aforesaid inwhich the units can be physically separated and can be operated as twoindependent high fidelity systems if enjoyment of high fidelityreproduction in two =diiferent rooms or locations is desired.

While simple sound reproduction systems have been built up usingseparately purchased units, such systems have necessarily been verylimited in their functions due 'to the problems of interconnection, evento persons skilled in electronics. Where more versatile systems aredesired, the interconnections previously required have been so complexthat it has not previously been feasible to mermhandise the separatecomponents.

These dilficulties of the past have been overcome in the presentinvention by the provision of two, preferably "matched, independent highfidelity sound reproduction systems or units adapted to be connected onopposite sides of two switches preferably having corresponding function-selecting positions and having simple connection means therebetweenadapted to carry signals in either direction between the units, thearrangement being such that the :flexibilityof the system is achieved inthe complexity of the switch connections and notin the complexity ofconnections between the units.

More particularly according to the invention, the con -nection betweenthe pair of switches may c mprise a single connection which anypurchaser may make, and .the switch connections comprise permanentfactory made vconnections in the individual units, the switching being2,983,795 Patented May 9, 1961 'ice such that the simple setting of thetwo switches to the particular function desiredautomatically makes thenecessary connections to deliver the signal in the respective directionover the single interconnection between the switches to produce thesystem function set by the switches.

Inasmuch as stereophonic sound, which is now an essential to the hi-fienthusiast, requires the provision of two sound channels or systems, thepresent invention, in providing the two sound systems locatedelectrically on the opposite sides of the pair of correspondingswitches, is not in any way unnecessarily increasing the cost of thesystem, yet by virtue of this arrangement and the simpleinterconnection, the two sound reproduction systems or units can bedivorced from each other and utilized separately.

In this latter connection, in the preferred form of the invention one ofthe sound units or systems is incorporated in an independently operabletape recording and playing unit incorporating one of the switch pair andhaving -a main head and a stereo head, the main head being connected sothat its output signal will play through the incorporated sound systemand the stereo head being connected so that its output signal will bedelivered to the switch, the sound system also being connected to theswitch so that signals to be delivered to or received from the externalsound system may be fed to and received from the switch.

Further according to the preferred form of the invention, the secondsound system is arranged to incorporate the other switch and isconnected therewith to receive signals from and deliver signals to theswitch, the second sound system incorporating plug-in facilities for aradio frequency tuner and record player which selectively may beoperated through the second sound unit as an independent hi-ficombination radio phonograph system or upon setting of the switch pairwith the connections therebe tween may utilize the sound system of thetape recording and playing unit for dual channel output, or the selectedsignal from the effectively independent radio phonograph systeminvolving the second sound unit may be recorded by the tape recorder.

These and other objects and features will become ape parent from thefollowing detailed description taken in conjunction with the acompanyingdrawings, in which:

Figure l is a block diagrammatic view illustrating a tape recording andreproducing unit provided with a function selecting switch in accordancewith the invention;

Figure 2 is a block diagrammatic view illustrating an independent audioamplifying and speaker unit provided with a function selecting switchhaving selecting positions corresponding to the switch of the unit ofFigure 1, the figure showing in perspective form radio tuner and recordplayer units arranged for plug-in connection with the audio amplifyingand speaker unit;

Figure 3 is a block diagram showing the units of Figures 1 and 2interconnected bya single connection between the function selectingswitches in accordance with the invention, the switches being positionedto obtainstereophonic sound;

Figure 4 is a view similar to Figure 3, 'but showing the switchespositioned to obtain tape reproduction;

Figure 5 is a view similar to Figures 3 and 4, but showing the switchespositioned to play and record the output from the radio tuner unit;

Figure 6 is a view similar to Figures 3, 4 and 5, with the switchespositioned to play and record the output from the record player unit;

Figure 7 is a view similar to Figures 3 to 6, but showing an alternativeswitch arrangement whereby the sound output from a television set isconnected to be played through the two units-of-Figures 1 and 2.

With reference to Figure L'a tape recording and re producing orplay-back unit is shown in very much simplified and block diagrammaticform, as comprising a tape 1 fedbetween reels 2. Associated with thetape is a main playing head3, which feeds an audio amplifier shown inblock form as comprising a main preamplifier circuit 4, a volume controlcircuit 5, a tone control circuit 6, a voltage amplifier 7, and a poweroutput 8, feeding through aplay-record switch 9 to a speaker unit,generally designated at 10. As shown, the speaker unit comprises aspeaker 11 and associated with the speaker 11 is a socket 12 providingfor plug-in connection through plug 13 of a more elaborate speakerassembly designated at 14. The speaker assembly 14 may comprise separateaccurate response speakers in the form of a suitable cabinet unit.

The play record switch 9 provides for the delivery of an output signalfrom the power output of the audio amplifier to be delivered through anequalizing network 15 to a record head which is shown as comprising thehead 3. The unit shown in Figure 1 is adapted for stereophonicplay-back, and in this connection it is provided with an auxiliary orstereo head 16, the output of which is connected to a stereopreamplifier 17 connected to a volume control 18. In stereophonic sound,it will be understood that two separate recordings which may be, forinstance, on the same tape if desired, are played simultaneously throughtwo sound systems so that a third dimension in the sound is achieved. Inthe present case, the main playing head 3 may be energized by onerecording on the tape 1, and played through the sound system comprisingthe audio amplifier 4, 5, 6, 7 and 8, and speaker unit 10, while thesecond recording is adaptedto be played through the stereo head 16 andthrough the sound system of the unit of Figure 2, as hereinafter morefully described.

According to the invention, the tape recording and play-back unit ofFigure 1 is provided with a function selecting switch designated at 19.The actual form of this switch may vary as desired, and the switchillustrated is merely an example of a workable switch arrangement tocarry out the invention. The switch is shown as having a contact 20 forexternal conn ction, preferably through a plug-in connection 21. Afurther contact 22 is connected to an input point of the audio amplifierindicated at 23, electrically in advance of the 'volume control circuit5. Another contact 24 is connected tothe output of the stereo volumecontrol 18. Another contact 25 is connected to an output point of theaudio amplifier of the unit of Figure 1, indicated at 26, electricallyimmediately ahead of the power output circuit 8.- Another contact 27 isconnected to an input jack 28 to which, if desired, a radio frequencytuner unit may be plugged.

A further contact 29 is shown connected to a further input jack 30, intowhich, for instance, the output of a record playing instrumentality maybe plugged.

A rotor unit 31, operated by a suitable handle or knob 32, is providedto selectively connect the contacts 22, 24, 25, 27 and 29 to theexternally connected contact 20, according to the function desired, andto connect the contacts 27 and 29 to the input contact 22 when the soundsystem of Figure 1 is to be utilized in the re production of signalsdelivered to the unit through the input jacks 28 and 30. a

Figure 2 illustrates a sound system comprising an audio amplifier brokenup into block form and shown as a volumec'ontrol circuit 33, feeding atone control circuit-34, feeding a voltage amplifier 35, feeding a poweroutput amplifier 36 connected to a speaker unit 37. The circuits 33, 34,35 and '36 ofthe unit or Figure 2 preferably have substantiallyidentical characteristics,with the circuits 5, 6, 7 and'8 of the unit ofFigure 1.

As in the case of the'unitof Figure l, the sound sys= tem of the unit ofFigure --2 is shown as employing as the speaker unit 37 a speaker 38which may form a permanent part of the unit, and an associated socket 39into which a more elaborate speaker assembly, indicated at 40, may beconnected by a plug 41. The speaker assembly 40 may comprise ,asuitagblecabinet unit as desired.

The audio amplifier comprised by the circuits 33 to 3 6 is shown asbeing energized from a power supply 42 in connection with an A.-C.source connecting plug 43 through a power transformer 44. The powersupply input through plug 43 is shown connected to a socket 45 intowhich an automatic record changer and pick-up unit indicated at.j46 isadapted to be plugged through corresponding plug-in member 47.

The record changer 46, of course, incorporates a driving motor which isillustrated by a field winding 48 and a control switch 49 associatedwith the socket 45 is provided to connect power through the socket, inthe position shown, to energize the record changing motor.

It will be understood that this unit may, if desired, be a stereo ortwo-channel record player unit.

Also connected to the power supply 42 is a socket 50, into which a radiotuner ,51 comprising, as will be understood in the art, a radiofrequency amplifier and detector, either of the A.M. or F.M. type, withor without intermediate frequency stages, is adapted to be plugged bymeans of the plug 52. Thus, the automatic record changer 46 and radiotuner 51 comprise separate units from the sound system of Figure 2,which separate units may be quickly connected to the sound system ofFigure 2 by plug-in connection.

In accordance-with the invention, the unit comprising the sound systemof Figure 2 is provided with a function selecting switch 53corresponding to the switch 19 of the unit of Figure 1, though not shownas of identical construction.

The switch 53 has a contact 54 for external connection throughaplug-inconnector 55. The plug-in connectors 21 and 55 of the functionselecting switches of the unitsof Figures 1 and 2am adapted to beconnected by a single plug-in connectorindicated at 56 in Figures 1 and2, which may comprise the usual cable connector having an outergrounding sleeve or conductor to connect the chassis of the two systemsofFigures l and 2 to a common ground and an inner signal carryingconductor 56'. The switch 53 has a further contact 57 in connection withan output point of the audio amplifier of the unit of Figure, 2indicated at 58 between the voltage amplifier circuit and the poweroutput circuit. A further contact 59 is connected to the input of thevolume control circuit 33. A further contact 60 isconnected to thesocket 50 of the radio tuner 51 and another contact 61 is adapted to beconnected -to the output of the record changer unit 46 through a plugeinconnection 62.

The switch 53 is provided witha rotor 63 operated by a handle orposition, selector element 64, the arrangement of the rotor and thestationary contacts 54,57, 59, 60 and 61 being such that the externallyconnected contact 54 is selectively connectedto the input and the outputconnected switchcontacts 59 and 57 respectively, according to theselected functioning of the unit of Figure 2, and the contacts 60 and 61are selectively connected to the input connected'contact '59 while theoutput connected contact 57 -is connected .to the externally connectedcontact 54 when the switch rotor 63 is turned to select radio or recordreproduction.

The interfunctioning of the tape recording and reproduction unit ofFigure 1 and the sound system comprising the unit of-Figufe '2 andplug-inassociatedunits 'comto 6; In Figure 3,"the two functionselectingswitches Hand 53 are shown connected by the single plug-in connector 56,and with the rotors of the switches set correspondingly to a stereoposition. In this position it will be seen that the output from the mainplaying head 3 of the tape recording and reproducing unit is connectedto play through the first sound system comprised by the audio amplifiercircuits 5, 6, 7 and 8 to produce an audio output from the speaker unit10. At the same time, the output from the stereo head 16 as deliveredfrom the stereo volume control circuit 18, is delivered to the stereocontact 24 of the first function selecting switch 19, and this lattercontact is in connection through the rotor with the externally connectedcontact 20 to deliver a signal to the externally connected contact 2; ofthe corresponding or second function selecting switch From the contact54 the signal is delivered through the input connected contact 59 to theaudio amplifier of the second sound system comprised by the circuits 33,34, 35 and 36 and the speaker unit 37 to produce an audio output fromthe speaker. Thus, with the switches set in the position of Figure 3,two recordings on the tape 1 are played through two separate soundsystems to pro- 'vide stereophonic sound.

In Figure 4, the rotors of the switches 19 and 53 have been turned tocorresponding tape positions. In this case, the output from the mainplaying head 3 of the tape unit is delivered through the first soundsystem to produce an output sound from its speaker unit 10. At the sametime, a signal from the output point 26 of the first sound system isdelivered to the contact 25 of the first function selecting switch 19,through the rotor of the switch to the externally connected contact 20,and through the single plug-in connector 56 to the externally connectedcontact 54 of the second function selecting switch 53.

The signal is then delivered through the rotor 63 of switch 53 to thecontact 59 which is connected to the input of the second sound systemcomprised by the circuits 33 to 36 and speaker unit 37. Thus, withswitches 19 and 53 in the tape position, the signal output from the tapewill be simultaneously played through the two sound systems. It is to benoted that the signal taken from the tape unit and delivered through thefirst function selecting switch 19 and to the second function selectingswitch 53, and from the latter switch to the input of the second soundsystem, is taken from an output point 26 located electrically after thevolume and tone control circuits 5 and 6 so that the settings of thevolume and tone control circuits in the tape unit will govern the volumeand tone in the electrically similar second sound system with which thesecond function selecting switch 53 is associated. Thus, the first soundsystem of the tape forms the master system, and the second sound systemis a slave thereto.

Figure 5 illustrates the relationship of the contacts and rotors of thefunction selecting switches 19 and 53 when they are moved tocorresponding radio positions. In this case, the output from the radiotuner is connected through contact 60 to contact 59 which delivers thesignal to the input of the second sound system comprised by the circuits33 to 36 and speaker unit 37. At the same time, the output point 58 ofthe second sound system is connected through contact 57 to theexternally connected contact 54 to deliver a signal in a directionreverse from that of Figures 3 and 4 to the externally connected contact20 of the first function selecting switch 19, and the signal isdelivered from this latter contact 54 to input connected contact 22 todeliver the signal to the input point 23 of the first sound system.

Thus, with the function selecting switches in the radio position, thesignal from the radio tuner 51 will be amplified simultaneously in thetwo sound systems, and the listener will have the benefit of the outputfrom the 6 speaker units 10 and 37 of both systems. Alternatively, ifdesired, the switch 9 may be operated to arrange for recording of theradio program on the tape 1.

In the case of the switch relations of Figure 5, the second sound systemnow becomes the master and the first sound system of the tape unitbecomes the slave, the reverse of that described in connection withFigure 4.

In Figure 6, the switches are shown as moved to the phono position, andin this case, the signal from the automatic record changer is deliveredby the second function selecting switch 53 to the input of the secondsound system, and is also delivered by the switch 53 from the outputpoint 58 to the first function selecting switch 19 and from this latterswitch to the input point 23 of the first sound system.

In the selecting of the operation of the two sound systems to play and/or record signals from the record changer 46, there is the additionaloperation of energizing the changer motor indicated by the field winding48 and for this purpose, the control switch 49 is shown ganged to thesecond function selecting switch 53 in Figure 2, the arrangement beingsuch that the motor is energized when the switch 53 is moved to thephone position.

With the relationship of the switches as shown in Figure 6, it will beunderstood that both sound systems will play the signal from the recordchanger and, if desired, by operation of the record switch 9, the signalfrom the record may be recorded on the tape 1. Where the unit of Figurel is divorced from the unit of Figure 2, it will be understood thatsignals from a radio tuner or a record player may be played through thesound system of the tape unit by plugging the radio tuner or the recordplayer into the input jacks 28 and 30, and the signals therefrom may berecorded, if desired, on the tape 1.

It will be understood that the operation of the switches to set them atthe various function selecting positions may, of course, be manual, ormay, if desired, be eifected through a suitable servo-mechanism so thatthe operation of one of the switches 19 or 53 will eifect desiredoperation of the other. Also, while the switches 19 and 53 have beenshown as rotary type switches, they may obviously be constructed in theform of push-button switches.

It will also be understood that the system as a whole and the individualcomponents or units making up the system are shown in simple form forpurposes of illustrating the combinations which may be achievedaccording to the invention by the use of the double function selectingswitches and the simple connection 56 therebetween, and that theindividual units may be as complicated as desired, and further units maybe added in the system. For instance, in Figure 7, an alternative systemembodying the invention is disclosed, but again the system employs apair of function selecting switches 19' and 53 which, in conjunctionwith a single connector 56, provide for a highly versatile high fidelitysystem. In this case, the switch 19' has additional contacts 65 and 66to provide for the delivery of an audio frequency signal from atelevision set 67 through the function selecting switches 19' and 53 toboth sound systems comprised by the circuits 5 to 8 and speaker unit 10,and circuits 33 to 36 and speaker unit 37 respectively.

In other respects, the system of Figure 7 corresponds to the systems ofFigures 3 to 6, with the switch rotor units 31 and 63 performing thesame function as the rotors 31 and 63 of switches 19 and 5 3, and withthe contacts 20', 22, 24, 25, 27' and 29' being connected in the samemanner as contacts 20, 22, 24, 25, 27 and 29 of switch 19, and contacts54, 57', 59, 60' and 61 of switch 53 being connected in the same manneras contacts 54, 57, 59, 60 and 61 of switch 53.

It will be understood that various modifications and arrangements ingrouping of units, the circuits of the assa'aes units themselves and thenuinber of units involved may be varied as desired in accordance with,and withoutdeparting from the scope of the invention as set forth in theappended claims. For instance, the tape recording and play-back unit maybearranged to record two tracks at the same time from sounds originatingfrom a stereo record player comprising a record playing device toreplace the conventionalrecord player 46, in which case it willbeunderstood that a, second signal carrying conductor corresponding tothe conductor 56 will be required but, of course, this conductor couldbe incorporated in the same cable 56 as the signal carrying condoctor56' not shown,

Further, of course, simultaneous broadcast of A.M.,

and TV could be recorded Where the tape recorded was arranged for twotrack recording.

What we claim as our invention is:

1. A high fidelity system comprising a first sound sys: tern comprisingan audio amplifier and speaker means, means for creating a signal to befed to said sound system, a first multi-position switch associated withsaid sound system, connections between said switch and a point of inputand a point of output from the audio amplifier of said sound system,said switch having a contact arranged for external connectionselectively connectable with one or other of the aforesaid switchconnections dependent, on the setting of said switch, a second soundsystem comprising an audio amplifier and speaker means corresponding tosaid first sound system, a second multiposition switch corresponding tosaid first switch associated with said second sound system, connectionsbetween said secondswitch and a point of input to and a point of outputfrom the audio amplifier of said second sound system, said second switchhaving a contact arranged for external connection selectivelyconnectable with one or other of the aforesaid second switch connectionsdependent on the setting of the said second switch, and means for'connecting the contacts arranged for external connectioniof saidswitches to connect the output of the amplifier of said first soundsystem to the input of the amplifier of saidsecond sound system seriallythrough said switches and vice versa.

2. A high fidelity system comprising two independently complete soundamplifying systems, each comprising signal generating means, an audioamplifier and speaker means and each incorporating function selectingswitch means with said switch means having function selecting positionsand each switch means having a contact arranged for external connectionselectively connectable to a point of input and a point of output of therespective system, and conductor means connecting said switch contactsthereby coupling said systems together serially through said,switcheswhereby to conduct a signal in either direction, seriallythrough said switch means between said systems dependent on energizationof said signal generating means and on the function selecting positionsof said switch means.

3. A system as claimed in claim 2 in which said switch contactsconnecting means comprises a single plug-in con nection.

4. A highvfidelity system comprising a first sound amplifying system,signal generating means for energizing said sound system, a first switchhaving function selecting switch positionsprovided with a contactarranged for external connection selectively connectable through saidfirst switch man input and an output point of said sound system, asecond independent sound amplifying system, signal generating means forenergizing said second soundsystem, a second switch having functionselecting switch positions corresponding to said first switch andprovided with a contact arranged for external connection selectivelyconnectable through said second switch to'an input and an output pointof said second sound system, signal generating means, for energizingsaid second sound system, and means serially connecting the contacts of:said switches arranged for external con; nect on whereby to conduct asignal in either direction serially through said switch means betweensaid systems dependent'on energization of said signal generating means.

and on the function selecting positions of said switches;

5 A system as claimed in claim 4 in which said signal generating meansfor energizing said first sound system comprises a tape reproduction andrecording instrumcii tality having a main playing head in connectionwithth e, input of said-first sound system, a recording headinconnection with the output of said first sound system and a stereohead in output connection with said first function selecting switch for'delivering a signal therethrough to said second function selectingswitch for one first switch position, andsaid second function selectingswitch has a corresponding switch position for delivering s aid lattersignal to the input of said second sound system.

6. A system as clairn'ed'in claim 4 in which-said signal generatingmeansfor energizing said first sound system comprises a tapereproduction and recording instrumentality connected for reproduction tothe input and for recording to the output of said first sound system.

7. A system as claimed in claim 6 in'which said signal generating meansfor energizing said second'sound sys tem comprises a radio tunerinstrumentality in plug in connection with the input of said. secondsound system.

8. A system as claimed in claim 6 in which said signal generating meansfor energizing said second sound system comprises a record playinginstrumentality in plug in connection with the input of said secondsound system.

9. A system as claimed in claim 8 in which said record playinginstrument hasv a motor -eleme nt having a power input plug inconnection with a power outlet of said second system, and a switchfor'saidmotor gangedto said second function selecting switch.

10. A sound reproduction and recording system comprising a first unit inthe form of a tape recording and play-back unit having a main playinghead connected to provide asignal input to a first audio amplifying andspeaker system-and a second playing head adapted to provide a separatesignal to a second audio amplifying system for producing stereophonicsound, said unit having a first multi-contact function selecting switchhaving a contact for'external connection, a contact in connection withan input point and a contact in connection with an output point of saidaudio amplifying system, and a contact in connection with an outputpoint from said second playing headfand a function selectingswitchelement having a plurality of function selecting positions forselectively connectingsaid three last-mentioned contacts to saidfirst-mentioned contact, and a second unit in the form of a secondindependent audio amplifying and speaker system having electricalcharacteristics substantially similar to said first audiosystem, saidsecond unit having a second multi-contact function selecting switchcorresponding to said first switch and having a contact for externalconnection, ,a contact in connection with an input. point and a contactin connection with an output point of said second audio amplifyingsystem, and a function selecting switch. element having a plurality offunction selecting positions corresponding to the positions of theaforesaid selecting switch element to connect the external contactor"said second switch to said second switch input connected contact whenthe external contact of said first switchis connected to an outputconnected contact of said first switch and vice versa, said units beingconnected by a plug-in connector extending between and seriallyconnecting the external contacts of said switches.

ll. A sound reproduction and recording system as claimed in claim 10, inwhich said external switch con tacts are detachably connected by aping-in connector comprising a single signal carrying conductor.

12: A sound reproduction and recording systernas claimed in claim 1 1 inwhich a third unit in the form of a"radio'fr'equency amplifying anddetecting'unitis in plug-in connection with said second unit to deliveran audio frequency signal to a further contact on said second switch,said first switch having a further contact corresponding to said lattercontact, said function selecting switch elements being adapted, on beingcorrespondingly moved to connect said respective further contacts tosaid respective external contacts, to connect a signal from said thirdunit to the input of said second audio amplifying system and the outputof said second audio amplifying system to the input of said first audioamplifying system.

13. A sound reproduction and recording system as claimed in claim 11 inwhich a third unit in the form of an automatic record changer andpick-up unit is in plugin connection with said second unit to deliver anaudio frequency signal to a further contact on said second switch, saidfirst switch having a further contact corresponding to said lattercontact, said function selecting switch elements being adapted, on beingcorrespondingly moved to connect said respective further contacts-tosaid respective external contacts, to connect a signal from said thirdunit to the input of said second audio amplifying system and the outputof said second audio amplifying system to the input of said first audioamplifying system.

14. A sound reproduction and recording system as claimed in claim 13 inwhich said third unit incorporates a motor in plug-in connection with asource of power common to said motor and said second audio amplifyingsystem, the power circuit of said motor having a control switch gangedto said second switch to effect energization of said motor when saidsecond switch function selecting element is moved to connect the signalfrom said record i0 changer and pick-up unit to the input of said secondaudio amplifying system.

15. A sound recording and reproducing system as claimed in claim 10 inwhich each of said audio frequency amplifying systems is provided with avolume control.

circuit and a tone control circuit and the connections between therespective switch contacts and the inputs of said audio amplifyingsystems is electrically in advance of said volume and tone controlcircuits and the connections between the respective switch contacts andthe outputs of said audio amplifying systems are electrically beyondsaid volume and tone control circuits whereby the one audio amplifyingsystem is adapted to be a master and a slave to the other audioamplifying system according to the settings of said function selectingswitch elements.

16. A sound reproducing and recording system as claimed in claim 10 inwhich switch means are provided to selectively connect an output pointof said first audio amplifying system to a tape recording element.

17. A sound reproducing and recording system as claimed in claim 10 inwhich each of said audio amplifying and speaker systems has a firstspeaker member and a separate plug-in speaker unit.

References Cited in the file of this patent UNITED STATES PATENTS2,611,618 Camras Sept. 23, 1952 2,620,405 Shickel Dec. 2, 1952 2,732,429Wolfe Jan. 24, 1956 2,778,874 Mueller Jan. 22, 1957 2,792,449 BottiniMay 14, 1957

